Saturday, October 18, 2008

Rain makes you fatter

There could be something in this but if so the Brits should be hugely fat. It rains all the time there. But they seem to be about average for weight, in fact

SUNSHINE not only makes you feel good, but now it has been revealed that it has powers of weight loss, as rain can cause people to gain weight. While it may be the only good news for the drought-ravaged farmers, a team from Aberdeen University found miserable weather made it harder for dieters to shed weight.

They found those who were overweight had lower levels of vitamin D - which is created when the body is exposed to sunlight. The amount of vitamin D in the blood influences the functioning of a hormone called leptin, which tells the brain when the stomach is full. The obese produced a tenth less vitamin D than those of average weight.

Heavy rain, particularly in rural areas, also raises the risk of catching the potentially fatal bug E-coli. The concern is that farmers' slurry contains E.coli O157 bacteria from cattle muck; heavy rain can wash the slurry into streams and form puddles; the bacteria can then be found in mud stuck to boots, or spread by pets.

The Daily Mail reports that people with old injuries maintain that their scars ache when the weather is threatening and the low atmospheric pressure can induce premature labor. Monica Seles, the tennis star who was stabbed in the back during a tennis tournament in Germany, told one interviewer that her scar would tingle when rain was coming.


Obese take less pleasure in eating

This sounds paradoxical but could be right. That differing brain response patterns could predict weight gain over as short a period as one year sounds fishy, though

OBESE people may have a diminished ability to experience the pleasure of eating, prompting them to overindulge to boost their satisfaction, according to a new study. The study, published this week in the journal Science, found that obese individuals may have fewer pleasure receptors in their brains, requiring them "to take in more of a rewarding substance such as food or drugs to experience the same level of pleasure as other people,'' said Eric Stice, a psychology researcher at the University of Texas (UT) at Austin and lead author of the study.

In a throwback to humankind's evolutionary past, the human brain releases the "pleasure chemical'' dopamine, a reward to the body for consuming life-sustaining nutrition. But the researchers theorise that weak "reward centres'' in the brain prompt obese people to eat more. "The research reveals obese people may have fewer dopamine receptors, so they overeat to compensate for this reward deficit,'' said Mr Stice, who has studied eating disorders and obesity for almost two decades.

Although past research has shown that biological factors play a major part in obesity, the study is one of the first to positively identify factors that increase people's weight gain risk in the future.

The researchers from UT, worked alongside scientists from the Oregon Research Institute, and brain scientists from the Yale University School of Medicine, Connecticut. Using a technique called functional Magnetic Resonance Imaging (fMRI), researchers examined the extent to which pleasure receptors in individuals were activated in response to a taste of chocolate milkshake versus a tasteless solution. The participants were next tested for the presence of a genetic variation linked to a lower number of the dopamine receptors. Researchers then tracked changes in the test participants' body mass index over a one-year period.

The results, said Mr Stice, were key for understanding weight gain and to helping at-risk individuals. "Although people with decreased sensitivity of reward circuitry are at increased risk for unhealthy weight gain, identifying changes in behavior or pharmacological options could correct this reward deficit to prevent and treat obesity,'' he said.


Another summary of the above work is given below, followed by the journal abstract:

What are the factors that increase an individual's risk of future weight gain? It has been hypothesized that obese individuals may have an underactive reward circuitry, which leads them to overeat in an effort to boost a sluggish dopamine reward system. Using brain imaging, Stice et al. (p. 449) discovered a relationship between activation of the striatum and ingestion of a tasty calorific liquid compared with a neutral liquid that could differentiate between obese and non-obese individuals. This differential activation was accentuated in individuals bearing the A1 allele of the dopamine D2 receptor gene, which is associated with reduced dopamine transmission in the striatum. This relationship predicted an individual's weight gain when measured a year later.


Relation Between Obesity and Blunted Striatal Response to Food Is Moderated by TaqIA A1 Allele

By E. Stice et al.

The dorsal striatum plays a role in consummatory food reward, and striatal dopamine receptors are reduced in obese individuals, relative to lean individuals, which suggests that the striatum and dopaminergic signaling in the striatum may contribute to the development of obesity. Thus, we tested whether striatal activation in response to food intake is related to current and future increases in body mass and whether these relations are moderated by the presence of the A1 allele of the TaqIA restriction fragment length polymorphism, which is associated with dopamine D2 receptor (DRD2) gene binding in the striatum and compromised striatal dopamine signaling. Cross-sectional and prospective data from two functional magnetic resonance imaging studies support these hypotheses, which implies that individuals may overeat to compensate for a hypofunctioning dorsal striatum, particularly those with genetic polymorphisms thought to attenuate dopamine signaling in this region.

Science 17 October 2008: Vol. 322. no. 5900, pp. 449 - 452

No comments: